Shaft position control mechanism



Sept. 30, 1952 E. TOTH ET AL 2,612,050

SHAFT POSITION CONTROL MECHANISM Filed March 27, 1947 Illj-zl DRIVING G I 2 23 2 T N'ING CONTROL SHAFT glwue/wfo'w GEORGE H. BURBAGE EMERICK TOTH Patented Sept. 30, 1952 SHAFT POSITION CONTROL MECHANISM Emerick Toth, Takoma Park, Md., and George H. s

Burbage, Washington, D. 0.

Application March 27, 1947, Serial No. 737,684

(Granted under the act of March 3, 1883, as

. amended April 30, 1928; 370 O. G. 757) 10 Claims.

This invention relates to a shaft position control mechanism, and more particularly to a mechanism for selectively controlling the angular position of a shaft with a high degree of accuracy.

While the present invention has wide application, as will be readily apparent, it is particularly intended for use in controlling the position of a tuning shaft such as employed in electronic apparatus, and specifically designed to be employed with a Vernier tuning control mechanism.

Another object of the present invention is to provide a new and improved shaft position control mechanism, and more particularly to provide a mechanism for selectively controlling the angular position of a shaft with a high degree of accuracy.

A further object of the present invention is to provide an improved shaft position control mechanism adapted for use in conjunction with a Vernier shaft.

Other objects and advantages of the'present invention will be apparent from the following detailed description taken in conjunction with the drawings, wherein:

Fig. '1 is a sectional view of the shaft control mechanism, taken along the line A-A of Fig. 2.

Fig. 2 is a bottom plan View, partially cut away, of the shaft control mechanism.

Briefly, this invention provides a means for exactly positioning a control shaft in any one of a number of positions without the aid of expensive machinery. A first drum may be mounted on or connected to the control shaft. A second drum is rotably mounted adjacent the first. drum and geared to the first drum so that rotation of the second drum will produce a slower rotation of the first drum and the associated control shaft. A mechanical stopping means is cooperatively associated with the first and second drums operative to arrest their rotation whenever any of a number of predetermined angular relations between the two drums have been reached. Additional means are associated with the drums for predetermining the angular relations of the two drums selected by the stopping means. Indicating means are associated with the stopping means for identifying each predetermined angular relation as it is reached.

' Referring now to the drawings, wherein a preferred embodiment of the invention is illustrated, it willbe seen that the shaft control mechanism of this invention includes two drums 5 and 6 which-are mounted on suitably spaced, parallel shafts l and 8, respectively, journalled between a pair of spaced, parallel, side plates 9 and [0 which form a generally rectangular housing for the mechanism. Spacer rods II are located at the four corners of the housing and extend between the side plates, their ends being suitably :ecured to the side plates to provide arigid strucure.

Each of the drums 5 and 6 consists of a plurality of disks l2, I2, and I2 and [3, I3 and I3", respectively, assembled between end plates BI and 62. As shown in Fig. 2, one end plate 62 may be made integral with the shaft and the otherend plate 6|, maybe attached thereto by a screwofifl. The disks are separated from each adjacent disk by spacer rings I4. Each disk has a large axial bore containing a washer 3, each washer 3 and spacer ring 14 is keyed to the shafts I and 8 by a key 4. The washers 3 slidably mount their respective disks and are employed to prevent the keys 4 which look the spacer rings I4 to the shafts l and B from also looking the disks to the shafts. Said washers are preferably constructed somewhat thinner than the disks in order not to interfere withthe lateral frictional engagement of the disks and of each disk with respect to its shaft may be individually adjusted without disturbing the other disks. Each disk has formed'in the periphery thereof of V-shaped notch l5.

Only three disks with their associated mechanism have been illustrated for the purpose of simplifying the drawing; it should be understood that the invention is not limited to that number.

Referring now to Fig. '2, it will be seen that the mechanism below the drums 5 and B in Fig. 1 has been cut away from the lowest disks I2 and I3 in Fig. 2 to illustrate their exteriors in plan view and the apparatus comprising drum 5 has been taken in cross-section through the center of tuning shaft ,1 to show the association of the r component parts of said drums. A gear train is provided whereby the'shafts I .and 8 may berotated in timed relation, comprising asmall pinion gear 20 keyed. to the lower endof the shaft 8, as viewed in 2, which drives a large spur gear 2| mounted on an idler shaft 22, suitably mounted on the side plate E0. The idler shaft 22 has also keyed thereto a second small pinion gear 23 which engages a second large spur gear 24 keyed to the end of the shaft '1. Thus it will be apparent that rotation of shaft 8 will cause rotation of shaft 1, the amount of rotation of shaft 1 with respect to that of shaft 8 depending on the gear ratio provided by the gear train described. It will be obvious, however, that to mount the gears so that the higher speed shaft is shaft I instead of shaft 8 would not be departing from the present invention. Another gear 19 may be keyed to shaft 8 whereby the tuning mechanism may be driven from an external source.

Since the shaft 1 and associated drum 5 retate at a substantially slower speed than the shaft 8 in the embodiment shown, the notches in the periphery of the disks forming the drum 5 will pass a given point only once for a number of revolutions of the shaft 8 depending on the gear ratio selected. For example, if the gear ratio provides a to 1 reduction, then the shaft 8 must be rotated up to 15 times in order to cause a notch on a given disk of the drum 6 to be aligned with any predetermined point at the same time that a notch on a corresponding disk of the drum 5 is aligned with a preselected point.

This condition is utilized in accordance with the present invention to provide a highly accurate and precise shaft control mechanism by employing in conjunction with the drums a number of pawls 26, shown in Fig. 1, correspondingto the number of disks on either drum. These pawls 26 are pivotally mounted on a shaft 21 journalled between the side plates 9 and I0 and located between the drums. Said pawls are adapted to rotate between the positions indicated in solid and dotted lines. The pawls are substantially T-shaped, each having a detent 28 integrally formed with the underside of one end of the cross portion 29 and extending toward the drum 5, and a second detent 30 integrally formed in a side of the mid-portion 3| of the pawl and extending toward the drum 6, as viewed; in these drawings. The opposite end of the cross portion 29 has bearing thereagainst one end of a small spring 33 so mounted as to urge the double pawl 26' to move as shown in Fig. 1, in a counterclockwise direction. The springs 33 are substantially semi-circular'in shape, with their opposite ends mounted on a comb member 34 pivotally supported at 36 between the side plates 9 and I!) by arms (only one of which is shown) to permit adjustment of the springs relative to pawls 26. Referring again to Fig. 2, by pivoting the comb member 34 in or outof the plane of the paper on its pivot arms 35 and .pivot 36, the springs 33are centered so that'a minimum torque is applied to the pawls when the pawls are in a disengaged position relative to. the disks. However, whena pawl begins to enter a notch, the associated spring is moved from its minimum torque position and acorrespondingly increased torque is applied to the pawl to urge the pawl firmly into the notch and thereby establish most accurate positioning.

The pawls are so mounted and shaped that when a notch on an associated disk I 2 is aligned with the corresponding pawl detent ZB and when a notch on a disk l3 of the drum S'is aligned with its corresponding detent 30, then the pawl may rotate about shaft 21 to cause the detents to enter the respective notches as shown in solid lines in Fig. 1, and thereby to arrest rotation of the drums. Since the drum 5 rotates only once for every 15 revolutions of the drum 5, this condition will not obtain except once for every 15 revolutions of the drum 6. Thus, it will be apparent that if the drum 5 be connected to a tuning control shaft, or be a part of the shaft to be controlled as shown, a highly accurate position control is effected.

The pawls 26 may be so shaped that when not detented, only the detent 28 slides along its respective disk l2 while the other detent 39 does not quite touch its disk 13. This provides a minimum of friction between detent and disk since only the detent 23 rides against its slow disk l2. In order that each detent will penetrate equally its respective notch l5, detent 30 will then have to move further than detent 2.8; accordingly, it is located further from the pivot shaft 21.

In order to facilitate the adjustment of the disks and also to permit free rotation of the disks without detenting the pawls when desired, a latching mechanism is provided comprising an open rectangular frame 40, shown in Fig. 1, pivotally mounted along its rear edge on a shaft 4| which is journalled between the spaced side plates 9 and [0. The frame is shown pivoted in a clockwise direction causing the transverse portion 42 thereof to engage lugs 43 shown atthe upper right end of the center arm portions 3! of the pawls 26. pawls are prevented from rotating in either direction. Pivoting of the frame is accomplished by rotating a shaft 44 journalled in a cover plate 45, mounted on the spaced plates 9 and I0. The shaft 44 has an eccentric pin 46 fixed to the inner end thereof which rides in a transverse slot formed on one end of a reciprocably mounted link arm 41, the link arm 41 being slidably supported on the side plate 9-. The other end of the link arm 41 has integrally formed therewith a member 50 which extends upwards at right angles, and the outer end of which is journalled to a short pin 5| which engages the outer ends of a short pivot arm 52 rigidly secured to the rear end of the-frame; Rotation of the shaft 44 then causes thelink 4 to move longitudinally and to pivot the frame 40 when the shafts I and 8 are rotated; It may be used in the following manner to setup a shaft: position. for future selection:

Any pawl desired for making this selection is chosen, the shafts are then rotated until this pawl detents. The latching mechanism is then engaged lockin this pawl down and preventing the others from detenting. The screws 60 are then loosened thereby permitting slippage of the disks with respect to their shafts as described above. With the'desired pawl locked in, the shafts are turned to their new selection'position, thereby.- sliding the appropriate pair of disks to a corresponding position. Now after tightening the screws 69, the new detent position will be set up for the desired pawl andthe When-engaged by the frame, the

detent positions of the other pawls will not have been changed. r

The position of the drums 5 and 6 is conveniently indicated as shown in Fig. 1 by affixing o'r forming small suitably numbered plates 54 to the ends of the midportions of the pawls 26 and providing a window 55 in the cover plate 44 so that when a pawl engages the disks, the associated numbered plate 54 will move into exposed position under the window 55.

The mechanism may be rotated by hand, at eachselected position a pawl will detent stopping the shafts and indicating the number of that position. The shafts are securely held but not locked by detenting of the pawls and may be rotated through any number of detent positions to any desired detent position, the pawls being designed to rise out of the notches upon further rotation of the shafts. The final positioning of the shaft at each detent position is reached automatically by the action of the springs 33 thus providing much more positive positioning than could be obtained by an entirely manual approach to each position.

Whether the mechanism is rotated by a moto or by hand, the rotating force may be removed as soon as the pawl starts entering the associated notches. The springs 33 will complete the positioningof the shafts and the possibility of hunting is thereby eliminated from the mechanism.

While but one embodiment of thisinvention has been shown and described, it will be understood that many changes and modifications may be made therein without departing from the spirit and scope of the present invention.

The invention described herein may be manu factured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

What is claimed is:

1. In a shaft position control device, a pair of juxtaposed rotatable drums each having a plurality of notches formed in the periphery thereof, means mechanically connecting said drums whereby rotation of one drum causes the other to rotate at a speeddifferent from that of the first drum, and pawl means positioned in intimate relation with the notches of each of said drums and operative upon its simultaneous engagement with a notch in each of said drums to arrest the rotation of said drums.

2. In a shaft position control device, a pair of juxtaposed rotatable drums each having a plurality of notches formed in the periphery thereof, said notches being positioned at selectable angular points along the length of said drums, means mechanically connecting said drums whereby rotation of one drum causes the other to rotate at a speed different from that of the first drum, and pawl means positioned in intimate relation with the notches of each of said drums and operative upon its simultaneous engagement with a notch in each of said drums to arrest the rotation of said drums.

3. In a shaft position control device, a pair of juxtaposed rotatable drums each having a plurality of notches formed in the periphery thereof, means mechanically connecting said drums whereby rotation of one drum causes the other to rotate at a speed different from that of the first drum, a plurality of pawls each having a first detent operative to engage a notch of one of said drums and a second detent operative to engage a notch of the other of said drums, said pawls being pivotably mounted and operative upon the simultaneous engagement of the two detents'of any single pawl with a notch in each of the drums to arrest the rotation of the drums;

4. In a shaft position control device, a pair of juxtaposed rotatable drums each having a plurality of notches formed in the periphery thereof, means mechanically connecting said drums whereby rotation of one drum causes the other to rotate at a speed different from that of the first drum, a plurality of pawls each having a first detent operative to engage a notch of one of said drums and a second detent operative to engage a notch of the other of said drums, said pawls being pivotably mounted and operative upon the simultaneous engagement of the two detents of any single pawl with a notch in each of the drums to arrest the rotation of the drums, and latching means operable to prevent the pivoting of said pawls in or out of their associated notches.

5. In a shaft position control device, a pair of juxtaposed rotatable drums each having a plurality of notches formed in the periphery thereof, means mechanically connecting said drums whereby rotation of one drum causes the other to rotate at a speed different from that of the first drum, a plurality of pawls each having a first detentoperative to engage a notch of one of said drums and a second detent operative to engage a notch of the other of said drums, said pawls being pivotably mounted and operative upon the simultaneous engagement of the two detents of any single pawl with a notch in each of the drums to arrest the rotation of the drums, latching means operable to prevent the pivoting of said pawls in or out of their associated notches, and indicating means associated with said pawls for indicating the relative position of said disks in'accordance with the entry of a pawl into a pair of notches.

6. In ashaft position control device, a pair of juxtaposed rotatable shafts, a plurality of disks assembled on each of said shafts, a notch formed in the periphery of each of said disks, means mechanically connecting said shafts whereby rotation of one shaft causes the other to rotate at a speed different from that of the first shaft. a plurality of pawls equal in number to the number of disks on each shaft, each of said pawls having 'a first and second detent associated respectively with a disk of one of said shafts and a disk of the other of said shafts, each pawl being pivotable whereby itsdetents may simultaneously enter the notches of their associated disks in accordance with the position of the disks so as to arrest the rotation of the shafts.

7. In a shaft position control device, a pair of juxtaposed rotatable shafts, a plurality of disks assembled on each of said shafts, a notch formed in the periphery of each of said disks, means mechanically I connecting said shafts whereby rotation of one shaft causes the other to rotateat a speed different from that of the first shaft, a plurality of pawls equal in number to the number of disks on each shaft, each of said pawls having a first and second detent associated respectively with a disk of one of said shafts and a disk of the other of said shafts, each pawl being pivotable whereby its detents may simultaneously enter the notches of their associated disks in accordance with the position of the disks so as to arrest the rotation of the shafts, resilient means associated with each of said pawlsoperable to cause one detentlof each pawl to press on the periphery'of its. associated disks and to increase. saidpressure as'a pawl moves into its associated notches.

8. In a shaft position control device. a pair of juxtaposed rotatable shafts, a .plurality .of disks assembled'on each of said: shafts, spacer means interposed between each of said. disks and arranged to rotate with the shafts to' permit individual adjustment. of the angular position of each of said disks, a. notch formed in the periphery of each of said di'sks,xineansmechan-v ically connecting said'shafts whereby. rotation of one shaft causes the otherto rotate-at a speed different from that of the first shaft, a plurality of pawls corresponding in number to the number of disks on each shaft, each of said pawls having detent meanspositioned in intimate relation to the corresponding disks of each shaft,

each pawl being pivotable so as to simultaneously enter the notches of its corresponding disks in accordance with the position of thedisks so as to arrest the rotation of the shafts, resilient means associated with each of said pawls :operable to cause one detent of each pawl to press on the periphery of its corresponding disk and to increase said pressure as a detent moves into its associated notches, and latching means operable to prevent the pivoting of'said pawls in or out of their respective-notches. v

9. In a shaft position control device, a pair of juxtaposed rotatable shafts, a plurality of disks assembled on each of said shafts, spacer means interposed between eachof said disks and arranged to rotate with the shafts to permit individual adjustment of the angular position of each of said disks, a notch. formed in the periphery of each of said disks, a gear train interconnecting said pair of shafts whereby the rotation of one shaft will cause rotation of the other shaft at a lower rate, a plurality of pawls corresponding in number to the number of disks on each shaft, each of said pawls having detent means positioned in intimate relation to the corresponding disks of each shaft, each pawl being pivotable so as to simultaneously enter the notches of its corresponding disks in accordance with theposition of the-disks so. as to arrest the rotation of the shafts, resilient means associated with eachof said pawls operable to cause one detent of each'pawl to press on the periphery of its corresponding disk and to increase said pressure as a detent moves into its associated notches, and latching means operable to prevent the pivoting of said pawls in or out of their respective notches.

10.1n-a shaft position control device, a pair of spaced parallel, rotatable shafts, a plurality of disks assembled on each of said shafts, spacer means interposed between each of said disks and arranged to rotate with the shafts to permit individual adjustment of the angular position of each of said disks, a notch formed in the periphery of each of said disks, a gear train interconnecting said pair of shaftswhereby the rotation of one shaft will cause rotation of the other. shaft at a lower rate, a plurality of pawls each having a pair of detents, said pawls being associated with said disks and being pivotable so that when suitable rotational relation of the shafts occur one" detent of one pawl enters the notch of .a disk on one shaft and the other detent of the same pawl enters the notch of a disk on the other shaft, resilient means, associated with each of said pawls operable. to cause one detent of each pawl to press on the periphery of its associated disk and to increase said pressure as apawl moves into its associated notches, latching means operable to prevent the pivoting of said pawls in and out of their associated notches, and indicating means associated with said pawls for indicating the relative position of said disks in. accordance with the entry of a pawl into a pair of notches.

, EMERICK -TO TH. I

GEORGE H. BURBAGE.

.' REFERENCES CITED The following references are of record in' the file of this patent:

I UNITED STATES PATENTS Germany June 6, 1926 

